Heat loss from a pipe in the wind 1

[sshep]

Friends,

I am looking for a method to estimate heat losses (or U value) from a pipe carrying liquid that considers wind speed and ambient temperature. I used to have a nomograph (also required pipe diameter, surface temp, etc), but I have lost this ancient resource. I am looking for either a paper on the subject, calculation, nomograph, or a modern equivalent.

Thanks,
sshep

 

[StoneCold]

There is a free software program called 3E Plus that will give you exactly what you need.


Regards
StoneCold

 

[ione]

Assuming the wall temperature equal to that of the fluid flowing inside the pipe you can treat this problem as a case of forced convection across circular rod and use the link below:

http://www.thermal-wizard.com/tmwiz/default.htm

 

[CJKruger]

sshep, historically many companies used the modified Langmuir equation. It was also used in the 1995 version of ASTM C680, but I seem to recall there are typo's in this standard.

I think newer versions of this standard use a more modern equation, but I still use the Langmuir equation.

 

[EmmanuelTop]

There is a handy spreadsheet at:

http://www.cheresources.com/insulation.xls

and followed with an interesting article at:

http://www.cheresources.com/insulationzz.shtml

For taking wind effects into account, you'll need to do a small calculation work for estimating U in the forced convection regime across a single cilinder/tube, and then replace the original value in the spreadsheet from above. It is good exercise and provides an insightful view how the presence of wind makes things completely different - when speaking about ambient heat losses.

http://antwrp.gsfc.nasa.gov/apod/astropix.html